In the following statements about functional dependency, which one is incorrect? ( )

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问题 In the following statements about functional dependency, which one is incorrect? (    )

选项 A、if X’

X, then X→X’
B、if X→Y and Y’

Y, then X→Y’
C、if X→Y and X’

X, then X’→Y
D、if X→Y and Y→Z, then X→Z

答案C

解析
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